Working with material under a magnetic field—especially a so-called <<intense>> magnetic field, that is, whereof the intensity is of the order of several Tesla or even tens of Tesla—forms the object of numerous scientific investigations.
A branch of operations known as <<magneto-science>> has emerged, the aim of which is to combine application of a magnetic field to a method for developing material.
The magnetic field is considered as an additional parameter which can influence either the morphology of the material during its manufacture or the kinetics of development methods used, as do parameters such as temperature, pressure or chemical composition.
In this sense, the magnetic field can be used to modify the usage properties of material.
If numerous effects of the magnetic field are still the object of fundamental studies, others are now already involved in industrial processes for synthesising materials.
In fact, superconductive magnets benefit regularly from major advances both in terms of performance and in terms of costs, which make their use feasible in industrial processes, especially in the field of development and treatment of metals.
Treatments conducted under intense magnetic field almost always involve thermal treatment for heating the object to be treated to a determined temperature.
Currently, heating devices comprise resistive or inductive heating elements.
Document WO 2011/012673 describes a device for treatment of an object under intense magnetic field comprising, for example, heating of the object followed by quenching.
However, since an electric current passes through the heating elements, coupling takes place between the superconductive magnet which generates the magnetic field and the heating elements, due to Laplace and Lorentz forces.
This coupling leads to rapid deterioration of the heating elements, requiring frequent replacement of said elements.
To this end, the article by K. Takahashi et al., <<Magnetic orientation of paraffin in a magnetic levitation furnace>>, Physica B 346-347 (2004), pp 277-281, proposes reflecting a beam emitted by a YAG laser onto two conical mirrors to form an annular beam perpendicular to the beam emitted by the laser about a sample to be heated.
However, this device is very bulky and is not compatible with the highly restricted volume imposed by devices for generating an intense magnetic field.
Finally, because of its two mirrors, this device is relatively heavy.
Also, there is a need to carry out so-called <<flash>> annealing, that is, with a very rapid rise in temperature to the preferred temperature to avoid any microstructural transformation of the material during heating.
So, the aim is to effect a rise in temperature of the order of several hundreds of ° C./s up to a maximal temperature which may be greater than or equal to 1600° C. under a magnetic field of 16 T.
However, the heating elements of known devices have thermal inertia which does not enable such a rapid rise in temperature, with the best results obtained to date being of the order of a few tens of ° C./s.
Also, available space in the intense magnetic field is highly restricted, the field hole of the superconductive magnet being of the order of 32 mm at ambient temperature.
It is therefore necessary to design a highly compact heating device adapted for inserting into this environment.
Another constraint to keep in mind in designing a heating device is that the object being treated must be able to be equipped with measuring instruments (sensors, probes, etc.) so that it can be characterised.
It is therefore necessary to provide sufficient volume around the object to accommodate these instruments.
The aim of the invention is therefore to overcome all these obstacles and provide a heating device for an object in an intense magnetic field, which permits very rapid rises in temperature (up to several hundreds of ° C./s) and which is sufficiently compact for inserting into the device for generation of the intense magnetic field.
This device must also be more robust than existing heating devices and minimise interactions with the magnetic field.